“Three millimeters off, it doesn’t work,” says Jason Schwalb, MD, a brain surgeon at Henry Ford Hospital in Detroit. “You have to take the patient back to the operating room and do it again.”

As we learn more about the architecture of the brain, surgeons are able to treat conditions like Parkinson’s disease that arise deep inside the brain.

Deep brain stimulation involves guiding an electrode to the area of the brain that has been damaged by Parkinson’s.

But the brain, like any living organ, is not static. It moves around, so an MRI image taken before the operation may no longer be accurate once the surgery has begun.

Traditionally, brain surgeons have used the patient’s own responses to guide them. There are no pain nerves inside the brain, so the patient can be awake during the operation.

But now surgeons are experimenting with an even better guide than the patient – an MRI machine inside the operating room, giving real-time images of the brain as the surgery progresses. It’s called iMRI. The “i” stands for intra-operative.

“This technology has a significant advantage in that you know with 100 percent certainty that you’ve got the electrode in the right place,” says Dr. Schwalb.

One additional advantage: the patient can be asleep.

Just as the GPS freed drivers from having to map out their route before beginning the journey, so the iMRI may free surgeons from depending on possibly outdated images before beginning a brain surgery.

“It wouldn’t surprise me if in 5 or 10 years, we’re doing things almost exclusively this way,” says Dr. Schwalb.